The present invention relates to a method for use in driving a liquid crystal display device.
A liquid crystal display device includes a liquid crystal display panel (also called a liquid crystal display element or a liquid crystal cell). The liquid crystal display panel includes a pair of substrates which face each other in an opposed manner, and liquid crystal composition is sandwiched between the two substrates. Pixels are formed on the substrate in a matrix array. These pixels constitute a display part of the liquid crystal display device.
Each pixel includes a pair of electrodes constituted of a pixel electrode and a counter electrode. By use of an electric field which is generated in response to a voltage applied between these electrodes, the optical transmissivity of the liquid crystal is controlled.
As examples of a liquid crystal display device, a vertical electric field type and an in-plane switching type are known. In the vertical electric field type, pixel electrodes are formed on one substrate and counter electrodes are formed on another substrate. In the in-plane switching type, the pixel electrodes and the counter electrodes are formed on the same substrate.
In these liquid crystal display devices, an AC driving method which periodically inverts the polarities of a voltage applied to the liquid crystal layer is performed. This AC driving method is adopted to prevent a deterioration of the liquid crystal which tends to occur when a DC voltage is applied to the liquid crystal. As one AC driving method, there is a known method in which a DC voltage is applied to the counter electrodes, and signal voltages of positive polarity and negative polarity, using a counter electrode voltage as a reference voltage, are alternately applied to the pixel electrodes.
Assuming a period in which all pixels of a liquid crystal display part are driven as one frame, there is a known driving method which changes over the polarities of voltages applied to pixel electrodes for every frame (hereinafter called a frame-inversion driving method). An example of the frame-inversion driving method is disclosed in Pub. No.: US 2002/0008800.